fuel heaters
 

The basic idea seems to be a good one. I've read about gains from such a set up, but there are many useless devices people think work.

I picked up 5 feet of fuel line at the hardware store this morning. Next i'll need to make a thermal transfer device and insulate my fuel rail. I was planing on something simple, like annealed copper tubing rapped around a coolant hose.

I'm still a little hesitant about the whole thing. It seems to me that a device such as this could cause the fuel to boil, which could be really bad. Does anyone know what temp gasoline boils at?

A quick googling tells me that your fuel pressure is between 30 and 46psi, so don't forget to account for that when you try to determine gasoline's boiling point.

A quick fidgeting of the numbers using 30psi shows that the lowest boiling point would be ~433?F for using the lowest boiling point I could find for gasoline. The highest boiling point would be ~472?F. this is all using the lowest boiling point I could find which was 100?F so your actual numbers will be higher.

Careful there, at 433 you are only 40 deg F from the autoignition temp of gasoline.

Don't forget that "gasoline" is not a simple chemical compound, it actually contains dozens or hundreds or different ingredients - some of which may boil off earlier than others. (I think a sunoco technical representative once told me that pump gas typically contains 175 different ingredients).

My brother ran into a situation in a Suburban a few years back, where he had an electrical fuel pump near the engine compartment. On a cross-country trip, he ran into a problem in the mountains where fuel was boiling inside the fuel lines - in addition to the gasoline being under suction (which promotes boiling) for an extended distance, the fuel line also ran right next to an exhaust pipe for a few feet. On big mountains (he was towing a camper trailer), the truck would bog down and lose all fuel delivery. The solution was to buy a "pusher" pump and install it at the back of the truck - since the fuel was now under pressure instead of under suction, it didn't boil off and he was able to maintain heavy throttle for extended periods.

Something I've thought about before is buying a length of 5/8" heater hose and trying to figure out a way to run 5/16" fuel line inside it for maybe 3 feet or so. That way I could preheat the gasoline to 180 degrees or so. It would basically be a 3-foot long heat exchanger. But I can't figure out a way to do it without having leaking coolant hoses (maybe gobs of RTV or something).

-BC

Totally forgot to add about fuel boiling off. When that pump cuts off you normally lose fuel pressure which means that fuel will boil off and you'll have fuel lines full of fuel vapor that needs pumped out before the car will start.

warm fuel has less power, some cars run fuel coolers if the gas line runs by the engine to much, for power and to pervent vapor lock. with less power you may need higher rpms to run the same speed, using more gas?
also i'm not an expert so i'll look forward to the rest of this post.

I don't buy into fuel temperature making a difference. However, if warm fuel does "have less power", it's because the fuel has expanded so you get less mass for a given volume of fuel. If that's the case, you won't get higher RPM, you'll just get more volume of fuel (same mass) injected as a result of data from your O2 sensors. Then you'll get the same power and the same fuel economy.

Anyway, there's two ways to adjust power and economy: by adjusting fuel used/energy produced, and by adjusting waste/energy lost. If warm fuel does "have less power", it's not because of wasted/lost energy; it's because of less fuel used.

I could see it reducing power if the intake is good at warming the air charge. The fuel vaporizing has a cooling effect as it turns to a gas. The TRD supercharging kit for the Tundras actually rely on it for knock prevention under full boost.

Why bother with unsafe and ineffective wrapped fuel lines? Get a plate heat exchanger from eBay and a few adapters for fuel and heater hose and you can have as much heat as you want.

This thread is poorly titled so I'm not surprised you didn't find it.

GasSavers: how i did it (fuel heat)

That's a good point about that thread title. I added to the title of the thread.

I think that holds true at WOT, you want to keep the entire intake charge as cold as possible to cram as much into the cylinder as possible (and colder = denser).

However, on an energy per mass basis, I think actually extract more energy from a given mass of hot fuel since you'll get a more complete combustion (hotter fuel = more volatile).

There may be tuning parameters that need to be changed - retard the timing (since combustion speed will be faster due to increased volatility), longer injector pulsewidth (less dense fuel = more time required for the same mass of fuel), but any modern engine should be able to make those minor tweaks automatically.

Also, Kyle raises an interesting point about the fuel boiling after engine shutdown, however I think many systems will retain pressure in the lines after shutdown. I know this happens on my car, but it could vary with different types of fuel pumps or leaky regulators or leaky injectors etc.

-BC

https://www.youtube.com/watch?v=BhmBNY19M_0 maybe wrap in muffler tape depending on temp....

also

https://www.youtube.com/watch?v=zb2df72N3FU

lawnmower running on vapors

If your car has a manual transmission and you have replaced the radiator with a universal aftermarket model, chances are you have the perfect setup for a fuel heater- just redirect your fuel line to include the transmission oil cooler circuit in the radiator.

Just to be safe, you may want to air pressure test the trans fluid cooler lines to be sure they will take 40 psi.

i wouldn't use the oil cooler in a rad for fuel heating. although it seems a nice idea, you have to remember that your fuel lines are much smaller than the oil cooler in the rad so there is firstly that volume change to contend with, secondly you're adding a lot more restriction to the system by adding extra lines and running it though the cooler - can the stock pump handle that and still provide adequate fuel? i don't know myself but i don't think i want to find out.

I don't expect big gains form this as you'll see posed on many web site, but I do suspect there to be some gains. The possible gains would be from improvements in the injectors spray, like the gains from acetone, or HHO.

As to fuel boiling when the car is not running; my car holds some pressure in the fuel line when off. I found this to be true (all over my shirt) last time i changed my fuel filter, so that is unlikely to cause major problems.

The radiator possibility seems like it would work relatively well, but is a more complex approach. Also I'd rather not mess with my trans. temp. The radiator doesn't only cool, but it heats the trans. oil as it transfers the water temp to the oil.

I was thinking of something similar to the one in the posed vid (the first one). But with the copper tube just rapped around the rubber hose, and as much of the aluminum connector that comes out of the block as possible. Also the addition of insulation rapping the coil and everything post-coil seems like it would make the system more worth wile than that guy's.

The pump should be more than okay with the added length and the change in diameter won't be an issue once pressure is up and the fuel line is full but as was stated I would worry about fuel pressure. Nothing in the radiator is designed with high pressure(20+psi) use in mind.